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Proper derivation of CH3NH3PbX3 (MAPbX3; where X = Cl−, Br−, I−) optical constants is a critical step toward the development of high‐performance perovskite devices. To date, the optical dispersions at all wavelengths have been inconsistently characterized by under‐approximating or omitting anomalous spectral features. Herein, a rigorous optical dispersion data analysis of single‐crystal MAPbBr3 involving variable‐angle spectroscopic ellipsometry data appended with transmission intensity data is presented. This approach yields a more robust derivation of the refractive index and extinction coefficient for both anomalous (absorptance) and normal (no absorptance) optical dispersion regimes. Using the derived optical constants, illustrative modeled perovskite solar cell device designs are presented in relation to nonrealistic designs prepared using representative optical constants reported in the literature. In comparison, the derived optical constants enables the modeling of layer thicknesses to maximize absorption by the active layer (MAPbBr3) and minimize parasitic optical absorptance by the nonactive layers at broad angles of incidence (≈0°–70°). This robust derivation of MAPbBr3 optical constants is expected to impact the optical dispersion data analysis of all perovskite analogs and expedite targeted development of, for example, solar cell, light‐emitting diode, photo‐ and X‐ray/γ‐ray detector, and laser system technologies.

Abstract Creating artificial matter with controllable chirality in a simple and scalable manner brings new opportunities to diverse areas. Here we show two such methods based on controlled vacuum filtration - twist stacking and mechanical rotation - for fabricating wafer-scale chiral architectures of ordered carbon nanotubes (CNTs) with tunable and large circular dichroism (CD). By controlling the stacking angle and handedness in the twist-stacking approach, we maximize the CD response and achieve a high deep-ultraviolet ellipticity of 40 ± 1 mdeg nm−1. Our theoretical simulations using the transfer matrix method reproduce the experimentally observed CD spectra and further predict that an optimized film of twist-stacked CNTs can exhibit an ellipticity as high as 150 mdeg nm−1, corresponding to a g factor of 0.22. Furthermore, the mechanical rotation method not only accelerates the fabrication of twisted structures but also produces both chiralities simultaneously in a single sample, in a single run, and in a controllable manner. The created wafer-scale objects represent an alternative type of synthetic chiral matter consisting of ordered quantum wires whose macroscopic properties are governed by nanoscopic electronic signatures and can be used to explore chiral phenomena and develop chiral photonic and optoelectronic devices.